1. Field of the Invention
This invention relates to cellulosic food casings, and more particularly, to shirrable food casings which are treated with an acid and a buffering agent to render the casings peelable from an encased food product, to impart improved skin formation on the food product, and to impart improved coloration to the food product.
2. Description of the Prior Art
Surface appearance is an important factor in the commercial and consumer acceptance of meat products. Consumers of meat emulsion products associate a bright pink or red color as being a normally acceptable surface characteristic for products such as frankfurters, bolognas, salamis, vienna sausages, and the like. This color is usually developed during cooking, curing, or processing of the meat emulsions, the emulsion comprising comminuted or chopped meat, meat products, spices and curing agents. Meat emulsions, when subjected to smoke house processing, are normally adequately cooked with regard to edibility and texture within standard conditions of time humidity and temperature for such emulsions. However, the thusly cooked and cured product generally does not develop an acceptable red cured meat color in its core during this processing period. Usually, the product must be subjected to further processing before the desired red cured meat color is obtained. This longer processing time increases the cost of manufacture and also results in a significant loss of weight of the product.
A process of treating synthetic sausage casing so that red color will develop on the surface of a meat emulsion stuffed therein is disclosed in U.S. Pat. No. 3,361,577 to Simon et al, wherein food casings are treated with an edible reducing agent. The reducing agents which can be employed therein are compounds selected from 1-ascorbic acid, isoascorbic acid, and metal salts and esters of these acids. In the practice of said process, an edible stabilizer is employed to assist in retarding oxidation of the reducing agent. Suitable oxidation inhibitors therein include the saturated aliphatic hydroxy acids such as citric acid, tartaric acid and the edible salts. However, it has been found that such treated synthetic food casings degrade during prolonged storage, thus limiting their utility.
Reddened color development is also important and desirable in raw unprocessed pork-containing meat products as for example, fresh pork or pork-beef sausage. The consumer prefers to see this color in the as-purchased product as an indication of freshness rather than rely solely on cooking for color development.
A cellulosic food casing having "easy peel" characteristics from insitu processed frankfurters after acid showering is disclosed by Rose et al in U.S. Pat. No. 3,674,511 wherein the food casing is treated with a soluble, edible salt, chelate or coordination compound of iron, aluminum, calcium or magnesium. Typical compounds include sulfates, citrates, malates, tartrates, gluconates, ascorbates, erythorbates, chlorides, and nitrates of iron, calcium or magnesium, either in the form of water soluble salts buffered to a pH at which the metal ion remains in solution, or in the form of mixed or double salts. It is disclosed therein that when solutions of these compounds are applied to frankfurter type casings during manufacture of the casings, the solutions must be buffered to a pH greater than 4 and typically above about 5.7 to prevent acidic degradation of the casings.
Food casings used in the processed food industry are generally thin-walled tubing of various diameters prepared from regenerated cellulose, cellulose derivatives, alginates, collagen and the like. Fibrous webs may also be embedded in these food casings and such casings are commonly termed in the art as "fibrous food casings". In general, these casings have multifunctional uses in that they may be employed as containers during the processing of the food product encased therein and also serve as a protective wrapping for the finished product. In the sausage meat industry, however, the preparation of various types of sausages ranging in size from smaller sausages such as frankfurters up to the larger sizes such as bolognas usually involves removing the casing from about the processed meat prior to final packaging. Peeling the casing from the processed sausage has presented major problems, particularly in the production of frankfurters where large numbers of the product are involved and the desire in commercial operations is to use high-speed, automatic stuffing and peeling machines.
The aforedescribed casings have also been used in the preparation of raw unprocessed pork-containing products as for example, fresh pork sausage or even fresh pork-beef sausage which typically contains substantial proportions of pork as for example, 45 wt%. High speed packing machines are also used in the manufacture of these products.
When the casing is removed from the meat mass, there is occasionally a tendency for some meat to adhere to the casing and be torn from the sausage with the casing, thereby causing surface marring of the sausage. In other instances, variations in the meat emulsion formulations or in the processing conditions can result in a degree of adherence of the casing to the product which hinders rapid removal of the casing from the product encased therein. The use of high-speed, automatic peeling machines in commercial operations, for example, such as those disclosed in U.S. Pat. Nos. 2,424,346 to Wilcoxon, 2,514,660 to McClure et al, 2,686,927 to Greg, and 2,757,409 to Parkers et al, makes it particularly essential that there be minimal resistance to the separation of casing from sausage, or the product will jam at the peeler or go through unpeeled. Less than complete removal of the casing necessitates the expense of hand sorting and peeling.
Heretofore many attempts have been made to provide casings having easy release characteristics. It is known in the art, as disclosed, for example, in U.S. Pat. Nos. 2,901,358 to Underwood et al, 3,106,471 and 3,158,492 to Firth, 3,307,956 and 3,898,348 to Chiu et al, 3,442,663 to Turbak, and 3,558,331 to Tarika, that the application of certain types of coatings to the inside wall of food casings may afford improvement in the release characteristics of the casing from the encased sausage product.
It has been common practice to improve the peelability characteristics of food casings from raw unprocessed pork-containing products to employ an acid shower to denature the meat and aid skin formation prior to chilling or freezing the meat. However, such an additional step can be time consuming and labor intensive. Thus, it would be desirable to eliminate this heretofore common step.
A limitation of the presently available raw unprocessed pork-containing products prepared in cellulosic food casings is that they have limited distortion resistance during physical handling after peeling of the casing. That is, the chilled or frozen products tend to break or deform on moderate handling.
Still another limitation of these presently available raw unprocessed pork-containing products is that they tend to lose the desirable reddened color or "bloom" after a short period following peeling of the cellulosic casing.
An object of this invention is to provide an improved cellulosic food casing article for use in the production of raw unprocessed pork-containing product.
Another object is to provide an improved method for producing unprocessed pork-containing product using cellulosic food casing.
Still another object is to provide an improved product comprising raw unprocessed pork-containing product in a cellulosic food casing, the latter being peelable with commercial machinery from the pork mass without damage thereto and without acid showering or thermal processing.
A further object is to provide a raw unprocessed pork-containing product having a denatured reddened outer skin with improved distortion resistance and longer bloom retention.
These and other objects are achieved by the present invention as described hereinafter.